In recent years, three-dimensional printing technologies, also referred as additive manufacturing (AM) technologies are rapidly developed and become increasingly popular. As known, there are various AM technologies. In accordance with the operating principle of the AM technology, a three-axis transmission system or a single-axis transmission system and nozzles cooperate to extrude a plastic material or other build material in order to produce a three-dimensional object. The overall quality of the three-dimensional object is dependent on nozzle control and size precision. The size precision is influenced by the transmission precision of the three-axis transmission system or the single-axis transmission system.
Nowadays, a fused deposition modeling (FDM) technology is an additive manufacturing technology commonly used for modeling, prototyping, and production applications. In the FDM technology, the build material is usually supplied in a filament form through a transmission system. That is, the time period of forming the three-dimensional object by the FDM technology is longer than other AM technologies. Therefore, it is an important issue to increase the precision and speed of the FDM technology. For increasing the printing speed and the printing precision, the stability and the positioning precision of the transmission system become more important.
For most three-dimensional printers, the belt transmission systems and the screw transmission systems are the mainstreams. FIG. 1 schematically illustrates a belt transmission system for a three-dimensional printer according to the prior art. As shown in FIG. 1, the belt transmission system 1 comprises a driving pulley 11, a driven pulley 12 and a transmission belt 10. During transmission, the tooth structures of the transmission belt 10 are repeatedly engaged with and disengaged from the tooth structures of the driving pulley 11 and the driven pulley 12. Once the tooth structure of the transmission belt 10 is engaged with and disengaged from the tooth structure of the driving pulley 11 or the driven pulley 12, the friction between the corresponding tooth structures and the assembling tolerance of the corresponding tooth structures may result in a backlash problem. Moreover, upon rotations of the driving pulley 11 and the driven pulley 12, the normal forces applied to the tooth structures may generate friction forces. Consequently, the long-term rotations of the driving pulley 11 and the driven pulley 12 may abrade the tooth structures of the transmission belt 10. Under this circumstance, the positioning precision is deteriorated. That is, even if the fabricating cost of the belt transmission system 1 is low, the backlash problem resulted from the belt transmission and the belt abrasion problem resulted from the long-term rotation may adversely affect the positioning precision.
FIG. 2 schematically illustrates a screw transmission system for a three-dimensional printer according to the prior art. During transmission of the screw transmission system 2, the rolling motions of plural small beads 21 allow a slide block 22 to be moved along a screw 23 in a reciprocating manner. Since the small beads 21 are precisely fabricated, the backlash of the screw transmission system 2 is lower than the belt transmission system. Moreover, since the transmission is performed by the rolling contact, the abrasion problem resulted from the long-term transmission is largely reduced. Although the screw transmission system can solve the problems of the belt transmission system, there are still some drawbacks. For example, since the screw transmission system is expensive, the fabricating cost of the three-dimensional printer is high.
Therefore, there is a need of provides a steel wire transmission system for a three-dimensional printer in order to overcome the above drawbacks.